Clinical pharmacology is the science of predicting the magnitude and time course (e.g., pharmacokinetics, or P.sub.k) of drug effect. Given that anesthetists spend their day administering low therapeutic index agents, clinical pharmacology is perhaps more important to anesthesiology than any other specialty. Anesthesia and reanimation necessitate a standard of precision and accuracy in drug administration not required in most areas of clinical medicine. Anesthetists depress the central nervous system to maintain the anesthetized state but then rapidly reanimate patients after an operation is complete. Although over-dosing every patient within the constraints of acceptable hemodynamic variables is one approach to assuring the patient is adequately anesthetized, it comes at the cost of slow emergence from anesthesia. The anesthetist must rely on drugs with rapid onset and predictable offset of effect to ensure maintenance of an anesthetic state with return of responsiveness and other vital function until the appropriate time. Anesthetists must therefore target drug levels that are within a relatively narrow therapeutic window to achieve the competing clinical imperatives of adequate anesthesia (without toxicity) and rapid emergence. Thus, from a practical aspect, the ultimate goal of clinical pharmacology is to provide anesthetists with the information they need to make rational and rapid decisions about the selection and administration of anesthetics.
Apparatus for modeling and displaying the modeled effects of a single drug on a subject are known in the art. These apparatus are useful in assisting those administering drugs, including health care professionals and other individuals, as well as automated systems that deliver drugs, with information that is useful in determining if, when, and how much of an additional dosage of the drug should be administered to the subject. Conventionally, such apparatus were configured to model the concentration of the drug in a subject's body, or “pharmacokinetics” (P.sub.k) of the drug. More recently, modeling techniques and apparatus have been used to model the effect site concentration of the drug, or “pharmacodynamic effect” or “pharmacodynamics” (P.sub.d) of the drug, which is a measure of the effectiveness of the drug on the body of a subject, may be modeled over time. Unfortunately, the often puzzling mathematical manipulations involved in estimating pharmacokinetic and pharmacodynamic parameters and the complex math required to build models that predict drug behavior have made use of these models in a clinical setting impractical.
As multiple drugs may be administered to a subject, more than one drug may have an effect on a patient or other subject during a particular point in time. Further, when multiple drugs are present in the body of a subject, they may have an effect on one another, or affect the subject in a different manner than any of the drugs alone would affect the subject. Nonetheless, modeling apparatus and techniques that are known in the art do not account for drug-drug interactions, or the combined effects of two or more drugs on the body of a subject.
Modeling techniques and apparatus that are known to the named inventors of the claimed subject matter do not consider the individual characteristics of a subject to which drugs are administered, the effects of multiple drugs on one another, or the effects of multiple drugs on a subject to which they are administered.
Without multiple sources of pharmacodynamic knowledge and monitoring, excessive dosages may waste drugs and, thus, money; prolong withdrawal of the subject from anesthesia, which may consume the availability of valuable operating room time; and even cause death of the subject. When anesthesia dosages are too small, the subject may become conscious or semi-conscious during an operation or other invasive procedure or the subject may be required to endure an excessive amount of pain, both of which may have a number of other negative consequential effects on the subject.
Moreover, anesthetists have been unable to effectively integrate the intricacies of kinetics and dynamics into their clinical practice, and instead, rely on training and experience to determine dosing.
Accordingly, there is a need in the art for techniques and apparatus that provide those who administer drugs or monitor the administration of drugs, in an intuitive manner, with additional information that would be beneficial in determining the proper amounts of one or more drugs that should be administered to a subject.